Patent GB-605257-A (GB)
Title: Improvements in or relating to electron discharge apparatus
IPC: H01J25/12
Filed: 1944-07-01
Abstract: 605,257. Electron beam apparatus; velocitymodulated tubes. SPERRY GYROSCOPE CO., Inc. July 1, 1944, No. 12592. Convention date, June 16, 1943. [Class 39 (i)] In a discharge tube comprising an electron beam density - modulated longitudinally in accordance with the incoming oscillation by a control grid or otherwise, means such as an apertured plate are provided whereby the outer part of the beam produced by lateral spreading due to mutual repulsion (which is most effective in the bunched regions) is cut off; the beam passing through a current modulated in phase 180 odegrees from the original bunching. In the apparatus shown in Fig. 4, the beam is produced by cathode 12 and collimating electrode 23 and the incoming wave from source 27 is communicated to grid 26. The beam after passing through aperture 19 in plate 18 operating as above stated passes to an earthed collector electrode 13 through grids 43, 42 connected across resonator 41 from which amplified oscillations are taken off by loop 48 and concentric transmission line 49. The grids 43, 42 may be capacitatively connected to the resonator instead of conductively. The grid 43 may be substituted by an apertured plate, which may in this case replace the plate 18. In the apparatus shown in Fig. 2, which may be used as a detector, the beam from cathode 12 is velocity modulated by means of earthed apertured plates 28, 30 and an intermediate cylindrical electrode 29 to which the incoming oscillations are communicated by a tuned circuit and is thereafter bunched by passage through earthed drift tube 34. The currentmodulated beam produced by passage through apertured plate 18 falls on collector 13 connected to a utilization device 28 with parallel resistor 16. The potential of the plate 18 may be adjusted by a potentiometer 35. In a modification, Fig. 5 (not shown), the beam after passing through the drift tube and obturating plate, passes through two earthed apertured plates spaced between which is a cylindrical electrode connected to a tuned output circuit. In another modification, Fig. 3 (not shown), the beam is velocity modulated by two grids connected across an external toroidal resonator, and bunched by passage through a drift tube; the apertured plate 18 may be formed at the end of the drift tube. The drift tube may be external to the envelope or may be formed as a conductive coating on it. The collector electrode is connected as in Fig. 2. In another modification, Fig. 6 (not shown), a system comprising two toroidal resonators separated by a drift tube is employed, the obturator plate 18 constituting the first grid of the catcher resonator. Local oscillations may be communicated to the first resonator as well as the incoming signal for heterodyne or homodyne reception. Feed-back means may be provided between the two resonators. In another modification, Fig. 8 (not shown), additional catcher resonators tuned to harmonic components of the incoming oscillation are provided; the end of the envelope is tapered to constitute the collector electrode. In the apparatus shown in Fig. 7, the grid members of the resonators 38<1>, 59<1> are replaced by openings 71, 72 formed by frusto-conical extensions of the resonator walls, the opening 72 also serving to cut off the debunched electrons. Feed-back 62 is provided; the apparatus may be used as an oscillator or as an autodyne converter. Specifications 518,015, 523,712, 541,477 and 548,725 are referred to.